Plasticizer composition and resin composition including the same

ABSTRACT

The present invention is a plasticizer composition which includes a trimellitate-based plasticizer and a citrate-based plasticizer, and does not contain epoxidized oil, and particularly, may provide a plasticizer composition which may improve physical properties such as migration resistance, tensile strength, an elongation rate, a retention characteristic and low-temperature resistance, required in the use of a plasticizer of a resin composition by improving problems inherent in a conventional plasticizer, and a resin composition including the same.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2017-0018590, filed on Feb. 10, 2017, the disclosureof which is incorporated herein by reference in its entirety.

TECHNICAL FIELD Technical Field

The present invention relates to a plasticizer composition and a resincomposition including the same.

Background Art

Conventionally, a plasticizer forms an ester through a reaction betweenan alcohol and a polycarboxylic acid such as phthalic acid or adipicacid. In addition, in consideration of domestic and internationalregulations for phthalate-based plasticizers harmful to humans, there isongoing research on plasticizer compositions that can replacephthalate-based plasticizers such as terephthalate-, adipate-, and otherpolymer-based plasticizers.

Meanwhile, in the compound industry requiring high thermal resistanceand low volatile loss as main physical properties, considering therequired physical properties, a suitable plasticizer should be used. Inthe case of PVC compounds for a wire and a cable, additives, forexample, a plasticizer, a filler, a stabilizer and a flame retardant areadded to a PVC resin depending on characteristics required for thecorresponding specifications, such as tensile strength, elongation rate,plasticization efficiency, volatile loss, retentions of tensile strengthand elongation.

At present, since diisodecyl phthalate (DIDP), which is typically usedin wire compound and automobile fabric industries, is an environmentalhormone under observation, and is restricted in use according to anenvironmental issue, a demand for the development of an eco-friendlyproduct to substitute for DIDP is increasing. However, since even manysubstitutes partially contain a phthalate-based material, they stillhave environmental problems.

For this reason, studies have been progressing to develop a product of anovel eco-friendly plasticizer composition, which has better physicalproperties than DIDP, to thereby ensure a vinyl chloride-based resincomposition which is free from environmental issues and has excellentquality.

PRIOR ART DOCUMENT Patent Document

(Patent Document 1) Korean Patent No. 10-0957134

DISCLOSURE Technical Problem

The present invention is directed to providing a plasticizer compositionwhich has excellent plasticization efficiency and migration resistance,is enhanced in tensile strength and an elongation rate, retention oftensile strength and retention of elongation, and has improvedlow-temperature resistance as a plasticizer applied to a resincomposition, and a resin composition including the same.

Technical Solution

To achieve the object, according to an exemplary embodiment, the presentinvention provides a plasticizer composition, which includes atrimellitate-based plasticizer represented by Formula 1 below; and acitrate-based plasticizer represented by Formula 2 below; and does notcontain epoxidized oil.

In Formula 1, R₁ to R₃ are each independently an alkyl group having 4 to10 carbon atoms.

In Formula 2, R₄ to R₆ are each independently an alkyl group having 5 to9 carbon atoms, and R₇ is hydrogen.

To achieve the object, according to an exemplary embodiment, the presentinvention provides a resin composition, which includes 100 parts byweight of a resin; and 5 to 150 parts by weight of the above-describedplasticizer composition.

Advantageous Effects

When being used in a resin composition, a plasticizer composition of thepresent invention can be expected to have excellent plasticizationefficiency and improved migration resistance, and reduced volatile lossand enhanced low-temperature resistance, as well as enhanced tensilestrength, elongation rate, retention of tensile strength and retentionof elongation.

MODES OF THE INVENTION

Hereinafter, the present invention will be described in further detailto help in understanding of the present invention.

The terms and words used in the specification and the claims should notbe interpreted as being limited to conventional or literal meanings, butshould be interpreted with meanings and concepts which are consistentwith the technological scope of the invention based on the principlethat the inventors have appropriately defined concepts of terms in orderto describe the invention in the best way.

Plasticizer Composition

According to an exemplary embodiment of the present invention, aplasticizer composition necessarily includes a trimellitate-basedplasticizer represented by Formula 1 below and a citrate-basedplasticizer represented by Formula 2, and does not contain epoxidizedoil.

In Formula 1, R₁ to R₃ are each independently an alkyl group having 4 to10 carbon atoms.

In Formula 2, R₄ to R₆ are each independently an alkyl group having 5 to9 carbon atoms, and R₇ is hydrogen.

When the trimellitate-based plasticizer and the citrate-basedplasticizer are included in the plasticizer composition, the upper limitof a weight ratio of the two materials may be 99:1, 95:5, 90:10, 85:15,80:20, 70:30 or 60:40, and the lower limit of a weight ratio of the twomaterials may be 1:99, 5:95, 10:90, 15:85, 20:80, 30:70 or 40:60. Theweight ratio of the two materials is preferably 90:10 to 10:90, morepreferably 80:20 to 20:80, and further more preferably 70:30 to 30:70.

The plasticizer composition according to an exemplary embodiment of thepresent invention does not include epoxidized oil, in other words, is aplasticizer composition not containing epoxidized oil. Here, the phrase“not containing epoxidized oil” means exclusion of the application ofepoxidized oil as a component of the plasticizer composition, and mayalso mean, even when the plasticizer composition is mixed with a resinin processing, epoxidized oil may be contained in the resin compositionat less than 5 parts by weight, preferably less than 3 parts by weight,and more preferably less than 1 part by weight with respect to 100 partsby weight of the plasticizer composition. However, it is not necessaryto exclude the addition of the epoxidized oil as a small amount ofstabilizer when the resin composition is prepared.

While the epoxidized oil may have a specific effect on a property suchas thermal resistance or oil resistance, a phenomenon in which a liquidplasticizer becomes a slurry at a low temperature, for example,approximately −5° C. or less, may occur, thereby causing a big problemin the storage and transfer of a product. Accordingly, when the resin isprocessed using the epoxidized oil-containing plasticizer, the transfer,delivery and processing of the plasticizer composition, and thelow-temperature resistance characteristic of the resin compositionprobably deteriorate.

Further, when the epoxidized oil is contained in the plasticizer whenbeing applied to a product requiring insulation performance, other thanthe above-mentioned problems, a phenomenon in which volume resistance isreduced may occur, compared with an eco-friendly plasticizer compositionwithout a conventional phthalate product and epoxidized oil.

Therefore, to solve the above-mentioned problems, the plasticizercomposition according to the present invention necessarily includes atrimellitate-based plasticizer and a citrate-based plasticizer asdescribed above, as the plasticizer composition does not containepoxidized oil, a low-temperature storage characteristic may be greatlyenhanced, and it can be expected that the low-temperature resistance ofthe prepared resin product is improved, and insulation performance isimproved due to enhanced volume resistance.

Trimellitate-Based Plasticizer

According to an exemplary embodiment of the present invention, theplasticizer composition may include a trimellitate-based plasticizer,which is represented by Formula 1 below and includes one or morematerials represented by Formula 1 below.

In Formula 1, R₁ to R₃ are each independently an alkyl group having 4 to10 carbon atoms.

The trimellitate-based plasticizer is a material capable of compensatingfor a terephthalate-based plasticizer as described above, and maycomplement a characteristic, for example, migration resistance orvolatile loss, which is achieved by a phthalate-based plasticizer, butnot achieved by the terephthalate-based plasticizer.

In the trimellitate-based plasticizer, R₁ to R₃ of Formula 1 may have 4to 10 carbon atoms, and each of R₁ to R₃ may be the same. If R₁ to R₃are different from each other, two of R₁ to R₃ are the same, but theother is a different alkyl group. For example, the alkyl group may be,for example, a normal butyl group, an isobutyl group, a normal pentylgroup, an isopentyl group, a normal hexyl group, a normal heptyl group,an isoheptyl group, a normal octyl group, an isooctyl group, a2-ethylhexyl group, a normal nonyl group, an isononyl group, a2-propylheptyl group, or an isodecyl group.

In addition, when, among the alkyl groups, a normal alkyl group, thatis, a linear alkyl group is applied, it has been known that acharacteristic such as low-temperature resistance becomes excellent.However, commercially, a branched isoalkyl group is excellent ineconomic feasibility. In the case of such a trimellitate-basedplasticizer, when the above-mentioned carbon number is satisfied, aneffect of improving plasticization efficiency, migration resistance,volatile loss, retention of elongation and stress migration can beexpected.

Citrate-Based Plasticizer

According to an exemplary embodiment of the present invention, theplasticizer composition may include a citrate-based plasticizer, whichis represented by Formula 2 below, and include one or more materialsrepresented by Formula 2 below.

In Formula 2, R₄ to R₆ are each independently an alkyl group having 5 to9 carbon atoms, and R₇ is hydrogen.

In the case of the citrate-based plasticizer, R₄ to R₆ of Formula 2 maybe each independently a pentyl group, an isopentyl group, a hexyl group,an isohexyl group, a heptyl group, an isoheptyl group, a normal octylgroup, a 2-ethylhexyl group, a normal nonyl group or an isononyl group,and R₄ to R₆ may be the same or different from each other.

The citrate in which R₄ to R₆ are different alkyl groups having 5 to 9carbon atoms may be, for example, a citrate having a combinedsubstituent of an isopentyl group and an isononyl group, a citratehaving a combined substituent of 2-ethylhexyl group and an isononylgroup, or a citrate having a combined substituent of an isopentyl groupand a 2-ethylhexyl group, or may be any other citrates in which R₄ to R₆have 5 to 9 carbon atoms, and which have a combined substituent of twoalkyl groups having different numbers of carbon atoms. Here, the alkylgroup may be linear or branched.

The citrate in which R₄ to R₆ are the same alkyl groups having 5 to 9carbon atoms may be, for example, triisopentyl citrate (TIPC), trihexylcitrate (THxC), triheptyl citrate (THpC), triisoheptyl citrate (TiHpC),tri(2-ethylhexyl) citrate (TEHC), or triisononyl citrate (TINC), or maybe any alkyl group having 5 to 9 carbon atoms.

Preferably, an alkyl group having 5 or more carbon atoms is applied, andwhen an alcohol having 5 to 9 carbon atoms, rather than those havingmore carbon atoms, even by a use of a small amount of such aplasticizer, the same or higher effects in plasticization efficiency andabsorption rate may be exhibited. In addition, the upper limit of thenumber of carbon atoms of the alkyl group may be 9, and when the numberof carbon atoms exceeds 9, due to an excessive increase in molecularweight, there is a concern about the deterioration of characteristicssuch as an absorption rate, plasticization efficiency, etc.

Meanwhile, when an acetyl group is present in the citrate-basedplasticizer, that is, R₇ is an acetyl group, a physical property of theplasticizer, particularly plasticization efficiency, may bedeteriorated, and additional equipment costs for treating waste citricacid generated as a byproduct may also be needed in a manufacturingprocess. When an acetyl group is introduced as described above, theremay be considerations such as the addition of process steps and theincrease in production costs due to the treatment of a byproduct.

In other words, in the citrate-based plasticizer, when R₇ of Formula 2is an acetyl group, compared with hydrogen, problems of reducedplasticization efficiency, the addition of an increased amount of theplasticizer to overcome the reduced efficiency, and increased productcosts thereby may accompany, and therefore, the citrate-basedplasticizer in which R₇ is an acetyl group may not be superior to theplasticizer in which R₇ is hydrogen in various aspects such asmarketability, economic feasibility and physical properties.

Preparation Method

In the present invention, a method for preparing the plasticizercomposition may be a blending method, and a composition may be preparedby a process of preparing a trimellitate-based plasticizer and acitrate-based plasticizer independently, and then mixing them together.

When the trimellitate-based plasticizer is prepared by directesterification, a process of applying one or more alcohols having R₁ toR₃ alkyl groups of Formula 1, for example, isopentyl alcohol, hexylalcohol, heptyl alcohol, 2-ethylhexyl alcohol, isononyl alcohol and2-propylheptyl alcohol, and reacting the alcohol(s) with trimelliticacid may be performed.

The direct esterification may be performed by adding trimellitic acid toan alcohol and adding a catalyst to induce a reaction under a nitrogenatmosphere; removing an unreacted alcohol and neutralizing an unreactedacid; and performing dehydration and filtration through vacuumdistillation.

In addition, the alcohol may be used at 150 to 500 mol %, 200 to 400 mol%, 200 to 350 mol %, 250 to 400 mol %, or 270 to 330 mol % with respectto 100 mol % of trimellitic acid.

Meanwhile, the catalyst used in the esterification may be, for example,one or more selected from acid catalysts such as sulfuric acid,hydrochloric acid, phosphoric acid, nitric acid, para-toluenesulfonicacid, methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid,butanesulfonic acid, and alkylsulfuric acid, metal salts such asaluminum sulfate, lithium fluoride, potassium chloride, cesium chloride,calcium chloride, iron chloride and aluminum phosphate, metal oxidessuch as a heteropoly acid, natural/synthetic zeolites, cation and anionexchange resins, and organic metals such as tetraalkyl titanate and apolymer thereof. Preferably, the catalyst is tetraalkyl titanate.

An amount of the catalyst used herein may vary according to its type,and as an example, a homogeneous catalyst may be used in a range of 0.01to 5 wt %, 0.01 to 3 wt %, 1 to 5 wt % or 2 to 4 wt % with respect to100 wt % of the total reactants, and a heterogeneous catalyst may beused in a range of 5 to 200 wt %, 5 to 100 wt %, 20 to 200 wt %, or 20to 150 wt % with respect to the total weight of the reactants.

Here, the reaction temperature may be in a range of 180 to 280° C., 200to 250° C., or 210 to 230° C.

To prepare the trimellitate-based plasticizer in a mixture, atrimellitate compound is prepared through direct esterification asdescribed above, and then mixed together, or two or more types ofalcohols may be applied in the direct esterification. Alternatively, thetrimellitate-based plasticizer may be prepared throughtrans-esterification in which a trimellitate compound such astri(2-ethylhexyl) trimellitate or triisononyl trimellitate is reactedwith an alcohol such as 2-propylheptyl alcohol, isopentyl alcohol orheptyl alcohol.

The term “trans-esterification” used herein refers to a reaction betweenan alcohol and an ester in which R″ of an ester is interchanged with R′of an alcohol as shown in Reaction Scheme 1:

For instance, when trans-esterification is performed using isononylalcohol as an alcohol and tri(2-ethylhexyl) trimellitate as atrimellitate, an isonoxide of the alcohol attacks all carbonyl carbonsin three 2-ethylhexyl (RCOOR″) groups present in the trimellitate, andthus a trimellitate in which the 2-ethylhexyl (RCOOR″) groups aresubstituted with isononyl groups may be formed; when carbonyl carbons intwo 2-ethylhexyl groups are attacked, three types of compounds in whichthe two 2-ethylhexyl groups are substituted with isononyl groups may beformed; when carbonyl carbons of one 2-ethylhexyl group are attacked,three types of compounds in which one 2-ethylhexyl group is substitutedwith an isononyl group may be formed; and tri(2-ethylhexyl) trimellitatemay remain as an unreacted portion that does not participate in thereaction.

According to an exemplary embodiment of the present invention, in thetrimellitate-based plasticizer prepared by the trans-esterification, acomposition ratio of compounds in the trimellitate-based composition maybe controlled according to an amount of an alcohol added.

The amount of an alcohol added may be 0.1 to 89.9 parts by weight,specifically 3 to 50 parts by weight, and more specifically 5 to 40parts by weight with respect to 100 parts by weight of the citrate.

According to an exemplary embodiment of the present invention, thetrans-esterification may be performed at a reaction temperature of 120to 190° C., preferably 135 to 180° C., more preferably 141 to 179° C.for 10 minutes to 10 hours, preferably 30 minutes to 8 hours, and morepreferably 1 to 6 hours. Within the above-mentioned temperature and timeranges, the terephthalate-based plasticizer, which is a mixture with adesired composition ratio, may be effectively obtained. Here, thereaction time may be calculated from the point of time at which thereaction temperature is reached after increasing the temperature ofreactants.

The trans-esterification may be performed in the presence of an acidcatalyst or a metal catalyst, which provides an effect of reducing thereaction time.

The acid catalyst may be, for example, sulfuric acid, methane sulfonicacid, or p-toluene sulfonic acid, and the metal catalyst may be, forexample, an organometallic catalyst, a metal oxide catalyst, a metalsalt catalyst or a metal itself.

The metal component may be, for example, any one selected from the groupconsisting of tin, titanium and zirconium or a mixture of two or morethereof.

The direct esterification and the trans-esterification may also be usedto prepare the above-described citrate-based plasticizer (using citricacid instead of trimellitic acid). In this case, like thetrimellitate-based plasticizer, the citrate-based plasticizer may alsobe prepared in a mixture of components at a predetermined ratio, and thecomposition ratio of the mixture produced may be controlled by adjustingan alcohol content as a reaction material. Other details of preparing acitrate plasticizer through direct esterification ortrans-esterification may be the same as those applied to the preparationof the trimellitate-based plasticizer.

In addition, as the reaction material, citric acid and trimellitic acid,which are carboxylic acid-based materials, may be replaced with an acidanhydride.

Meanwhile, the plasticizer composition may be prepared by preparing eachcomponent independently and then blending the components, or throughsimultaneous esterification with a component mixture.

Specifically, when alkyl groups having the same number of carbon atomsare intended to be applied to the citrate-based plasticizer and thetrimellitate-based plasticizer, the plasticizer may be prepared throughdirect esterification of an acid mixture of citric acid and trimelliticacid with an alcohol having a specific alkyl group, and in this case, aplasticizer composition in which the alkyl groups of the citrate and thetrimellitate have the same number of carbon atoms may be obtained.

That is, when the same alcohol is used, a simultaneous reaction betweentwo or more acids or acid anhydrides and an alcohol may be acommercially economical method.

According to another exemplary embodiment of the present invention,there is provided a resin composition prepared by mixing 5 to 150 partsby weight, 20 to 100 parts by weight, 30 to 80 parts by weight or 40 to70 parts by weight of the plasticizer composition prepared as describedabove with a resin, with respect to 100 parts by weight of the resin.

The resin may be selected from ethylene vinyl acetate, polyethylene,polypropylene, polyketone, polyvinyl chloride, polystyrene,polyurethane, and a thermoplastic elastomer.

In addition, the resin composition may be mixed with various additivessuch as a thermal stabilizer, a stabilizer, a lubricant, a filler, etc.,and the type or content thereof may be determined as known in the art.

The resin composition prepared as described above may provide a resincomposition effective in both of calendering and compound formulation,and the resin composition may be applied in, for example, manufacture ofwires, flooring materials, interior materials for automobile, films,sheets, or tubes.

EXAMPLES

Hereinafter, to explain the present invention in detail, the presentinvention will be described in detail with reference to examples.However, examples according to the present invention may be modified ina variety of different forms, and the scope of the present inventionshould not be construed as being limited to the examples to be describedbelow. The exemplary embodiments of the present invention are providedfor those of ordinary skill in the art to more fully understand thepresent invention.

<Preparation of Trimellitate-Based Plasticizer>

Preparation Example 1 Preparation of Tributyl Trimellitate (TBTM)

1,112 g of tributyl trimellitate (yield: 98%) was finally obtained using576.3 g of anhydrous trimellitic acid and 866 g of n-butyl alcohol asreaction materials.

Preparation Example 2 Preparation of Triisopentyl Trimellitate (TIPTM)

1,236 g of triisopentyl trimellitate (yield: 98%) was finally obtainedusing 576.3 g of anhydrous trimellitic acid and 1,030 g of isopentylalcohol as reaction materials.

Preparation Example 3 Preparation of Trihexyl Trimellitate (THxTM)

1,360 g of trihexyl trimellitate (yield: 98%) was finally obtained using576.3 g of anhydrous trimellitic acid and 1,196 g of hexyl alcohol asreaction materials.

Preparation Example 4 Preparation of tri(2-ethylhexyl) trimellitate(TEHTM)

1,607 g of tri(2-ethylhexyl) trimellitate (yield: 98%) was finallyobtained using 576.3 g of anhydrous trimellitic acid and 1,521 g of2-ethylhexyl alcohol as reaction materials.

Preparation Example 5 Preparation of Triisononyl Trimellitate (TINTM)

1,731 g of triisononyl trimellitate (yield: 98%) was finally obtainedusing 576.3 g of anhydrous trimellitic acid and 1,685 g of isononylalcohol as reaction materials.

Preparation Example 6 Preparation tri(2-propylheptyl) trimellitate(TPHTM)

1,855 g of tri(2-propylheptyl) trimellitate (yield: 98%) was finallyobtained using 576.3 g of anhydrous trimellitic acid and 1,852 g of2-propylheptyl alcohol as reaction materials.

<Preparation of Citrate-Based Plasticizer>

Preparation Example 7 Preparation of Triisopentyl Citrate (TIPC)

1,183 g of triisopentyl citrate (yield: 98%) was finally obtained using576 g of citric acid and 1,030 g of isopentyl alcohol as reactionmaterials.

Preparation Example 8 Preparation of Trihexyl Citrate (THxC)

1,307 g of trihexyl citrate (yield: 98%) was finally obtained using 576g of citric acid and 1,196 g of hexyl alcohol as reaction materials.

Preparation Example 9 Preparation of tri(2-ethylhexyl) citrate (TEHC)

1,554 g of tri(2-ethylhexyl)citrate (yield: 98%) was finally obtainedusing 576 g of citric acid and 1,521 g of 2-ethylhexyl alcohol asreaction materials.

Preparation Example 10 Preparation of Triisononyl Citrate (TINC)

1,679 g of triisononyl citrate (yield: 98%) was finally obtained using576 g of citric acid and 1,685 g of isononyl alcohol as reactionmaterials.

Plasticizer compositions of the examples were prepared by mixing thematerials prepared in Preparation Examples 1 to 10, and then theplasticizer compositions of the examples, comparative examples andreference example were summarized in Table 1 below. Evaluation of thephysical properties of the plasticizer compositions was performedaccording to the test items below. All of materials besides thematerials prepared in the preparation examples are manufactured by LGChem Ltd.

TABLE 1 Plasticizer A Plasticizer B Plasticizer C Example 1 TBTM 60 TINC40 — Example 2 TIPTM 50 TINC 50 — Example 3 THxTM 40 TEHC 60 — Example 4TEHTM 30 THxC 70 — Example 5 TINTM 20 TIPC 80 — Example 6 TPHTM 10 TIPC90 — Example 7 TEHTM 70 TIPC 30 — Example 8 THxTM 80 TEHC 20 — Example 9TBTM 90 TINC 10 — Reference DIDP¹⁾ 100 — — Example Comparative TPHTM 100— — Example 1 Comparative TBTM 100 — — Example 2 Comparative — TIPC 100— Example 3 Comparative — TINC 100 — Example 4 Comparative TEHTM 30TBC²⁾ 70 — Example 5 Comparative TEHTM 70 TUDC³⁾ 30 — Example 6Comparative TEHTM 70 ATIPC⁴⁾ 30 — Example 7 Comparative TBTM 60 ATINC⁵⁾40 — Example 8 Comparative TIPTM 50 TINC 50 ESO⁶⁾ Example 9 ComparativeTINTM 20 TIPC 80 ESO⁶⁾ Example 10 ¹⁾DIDP: Diisodecyl phthalate ²⁾TBC:Tributyl citrate ³⁾TUDC: Triundecyl citrate ⁴⁾ATIPC: Acetyl triisopentylcitrate ⁵⁾ATINC: Acetyl triisononyl citrate ⁶⁾Addition of 20 parts byweight of epoxidized soybean oil (ESO) with respect to 100 parts byweight of the sum of plasticizers A and B

<Test Items>

Measurement of Hardness

Shore hardness (Shore “A”) was measured at 25° C. under conditions of 3T and 10 s according to ASTM D2240.

Measurement of Tensile Strength

According to ASTM D638, each specimen was pulled at a cross head speedof 200 mm/min (1T) using a tester U.T.M (Manufacturer; Instron, ModelNo.; 3345), until the specimen was broken. Tensile strength wascalculated as follows:

Tensile strength (kgf/cm²)=[Load value (kgf)/Thickness (cm)]×Width (cm)

Measurement of Elongation Rate

According to ASTM D638, each specimen was pulled at a cross head speedof 200 mm/min (1T) using U.T.M until the specimen was broken. Anelongation rate was calculated as follows:

Elongation rate (%)=(Length after elongation/Initial length)×100

Measurement of Migration Loss

An experimental specimen having a thickness of 2 mm or more was obtainedaccording to KSM-3156, and a glass plate and wax paper were attached toboth sides of the specimen, respectively, followed by applying a load of2 kgf/cm². The specimen was maintained in a forced convection oven (80°C.) for 72 hours, then taken out of the oven, and cooled at roomtemperature for 4 hours. Afterward, following the removal of the glassplate and the wax paper attached to both sides of the specimen, theweights of the specimen before and after the maintenance in the ovenwere measured to calculate a migration loss by the equation below:

Migration loss (%)=[(Initial weight of specimen at roomtemperature−Weight of specimen after being maintained in oven)/Initialweight of specimen at room temperature]×100

Measurement of Volatile Loss

The prepared specimen was processed at 121° C. for 168 hours, and aweight of the specimen was measured:

Volatile loss (wt %)=[(Initial weight of specimen−Weight of specimenafter processing)/Initial weight of specimen]×100

Measurement of Retentions of Tensile Strength and Elongation

Measurement of retentions of tensile strength and elongation was carriedout by applying heat to specimens at 121° C. for 168 hours and measuringthe retentions of tensile strength and elongation remaining in thespecimens, and measurement methods are the same as those for tensilestrength and an elongation rate.

Measurement of Low-Temperature Resistance

Temperatures at which three of five specimens previously manufacturedwere broken by an impact after they had been maintained at a specifictemperature for 3 minutes were measured.

Experimental Example 1 Evaluation of Physical Properties 1

Specimens were manufactured using mixed plasticizer compositions of theexamples and comparative examples listed in Table 1.

To manufacture a specimen, referring to ASTM D638, with respect to 100parts by weight of a polyvinyl chloride resin (PVC (LS100)), 50 parts byweight of each of the plasticizer compositions prepared in the examplesand the comparative examples, 5 parts by weight of RUP 144 (Adeka KoreaCo., Ltd.) as a stabilizer, 40 parts by weight of Omya 1T (Omya Inc.) asa filler, and 0.3 part by weight of St-A (Isu Chemical, Co., Ltd.) as alubricant were blended and mixed at 700 rpm and 98° C. Specimens weremanufactured by processing the mixture using a roll mill at 160° C. for4 minutes, and compressing the resulting product using a press at 180°C. for 3 minutes (low pressure) and 2.5 minutes (high pressure).

The specimens were evaluated for each of the test items, and the resultsare shown in Table 2 below.

TABLE 2 Retention of Retention Low- Tensile Tensile Elongation ofMigration Volatile temperature Hardness strength strength rateelongation loss loss resistance (Shore “A”) (kgf/cm²) (%) (%) (%) (%)(%) (° C.) Example 1 87.8 172.3 102.4 310.2 95.6 0.89 2.67 −30 Example 288.1 169.8 99.6 308.1 88.3 1.46 2.49 −29 Example 3 88.2 173.5 101.2307.3 95.8 1.50 2.07 −29 Example 4 88.7 175.8 98.6 298.7 99.5 1.62 2.54−30 Example 5 88.0 178.2 103.4 310.0 98.5 1.24 2.89 −30 Example 6 88.1179.8 98.0 302.8 95.9 0.90 2.72 −29 Example 7 88.5 178.9 96.8 305.8 96.01.90 1.50 −30 Example 8 86.9 168.9 93.7 280.4 96.1 0.77 1.68 −31 Example9 85.7 165.3 95.4 311.8 92.5 0.56 3.84 −32 Reference 89.1 160.2 90.3276.1 81.1 1.84 7.35 −26 Comparative 93.4 180.3 92.3 254.0 88.7 2.751.47 −25 Example 1 Comparative 85.0 151.3 93.4 302.4 74.2 2.60 5.20 −32Example 2 Comparative 87.8 163.4 88.2 303.4 85.1 1.95 3.67 −29 Example 3Comparative 93.0 172.0 90.5 260.3 80.4 2.80 3.45 −28 Example 4Comparative 88.1 162.4 80.1 288.7 76.5 2.41 8.61 −30 Example 5Comparative 95.4 178.0 93.5 230.4 93.4 3.55 1.20 −25 Example 6

Referring to Table 2, in the case of Examples 1 to 9, where atrimellitate-based plasticizer and a citrate-based plasticizer, whichare materials in which an alkyl group having a proper number of carbonatoms is bonded, were suitably mixed, it can be confirmed that theplasticizers exhibited the same or superior physical properties,compared with DIDP as a reference. DIDP is a plasticizer product thathas been widely used, and although having a high quality, DIDP causes anenvironmental problem as a phthalate-based product. That is, it isconfirmed that all physical properties of the plasticizer compositionsof Examples 1 to 9, compared with DIDP, can be improved to the same orhigher levels as well as having environmental advantages.

However, it can be confirmed that, in contrast to Examples 1 to 9, whenthe trimellitate-based plasticizer or citrate-based plasticizer issolely used without mixing, migration loss is noticeably decreased ascompared with DIDP, and Comparative Example 1 exhibits significantlylower plasticization efficiency (hardness), elongation rate andlow-temperature resistance than Examples 1 to 9, and even than theconventional product DIDP. In addition, it can be confirmed that,compared with Examples 1 to 9, Comparative Example 2 is significantlydecreased in retentions of tensile strength and elongation, ComparativeExample 3 is significantly decreased in retention of tensile strength,and Comparative Example 4 is significantly decreased in plasticizationefficiency and retention of elongation.

Further, it is apparent that in the case of Comparative Examples 5 and6, which do not satisfy the range of the number of carbon atoms, exhibita very low level of migration loss, and it can be confirmed thatComparative Example 5 has 4 citrate-based carbon atoms, not satisfying 5to 9 carbon atoms, and has a volatile loss four times higher than theexamples, and therefore a considerably large amount of the plasticizerdisappears during a heating process, and retention of tensile strengthis also at a very low level. In addition, in Comparative Example 6, asthe citrate-based plasticizer has more than 9 carbon atoms, it can beconfirmed that the plasticization efficiency and the elongation rate aresignificantly decreased, and the low-temperature resistance is also at alow level.

Experimental Example 2 Evaluation of Physical Properties 2 (DifferenceAccording to Absence and Presence of Acetyl Group)

Specimens were manufactured as described in Experimental Example 1 usingthe mixed plasticizer compositions of the examples and the comparativeexamples listed in Table 1 and evaluated for each test item. The resultsare shown in Table 3 below.

TABLE 3 Retention of Retention Low- Tensile tensile Elongation ofMigration Volatile temperature Hardness strength strength rateelongation loss loss resistance (Shore “A”) (kgf/cm²) (%) (%) (%) (%)(%) (° C.) Example 1 87.8 172.3 102.4 310.2 95.6 0.89 2.67 −30 Example 788.5 178.9 96.8 305.8 96.0 1.90 1.50 −30 Reference 89.1 160.2 90.3 276.181.1 1.84 7.35 −26 Comparative 89.7 170.2 95.0 292.5 95.1 2.20 1.45 −27Example 7 Comparative 88.5 158.3 92.6 295.4 94.0 1.35 2.60 −27 Example 8

Comparative Examples 7 and 8 are prepared by using the plasticizersprepared by bonding an acetyl group to each of the citrate-basedplasticizers applied in Examples 1 and 7, respectively, and referring toTable 3, when an acetyl group-bonded citrate is applied, it can beconfirmed that Comparative Examples 7 and 8 were inferior to theconventional product DIDP in some of the physical properties, and wereinferior to Examples 1 and 7 in all physical properties.

In addition, in the case of an acetyl group-binding citrate-basedplasticizer, there is a considerable economic loss due to a complicatedmanufacturing process and waste acetic acid, and an environmentalproblem caused by the waste acetic acid has not been solved. Therefore,not only in terms of performance, but also economic and environmentalaspects of the plasticizer, it can be confirmed that it is preferable toapply a plasticizer to which an acetyl group is not bonded.

Experimental Example 3 Evaluation of Physical Properties 3 (DifferenceAccording to Addition of Epoxidized Oil)

Specimens were manufactured using the mixed plasticizer compositions ofthe examples and comparative examples listed in Table 1 as described inExperimental Example 1 and evaluated for each test item. The results areshown in Table 4 below.

TABLE 4 Retention of Retention Low- Tensile tensile Elongation ofMigration Volatile temperature Hardness strength strength rateelongation loss loss resistance (Shore “A”) (kgf/cm²) (%) (%) (%) (%)(%) (° C.) Example 2 88.1 169.8 99.6 308.1 88.3 1.46 2.49 −29 Example 588.0 178.2 103.4 310.0 98.5 1.24 2.89 −30 Reference 89.1 160.2 90.3276.1 81.1 1.84 7.35 −26 Comparative 88.7 160.4 93.4 288.5 87.2 1.302.41 −24 Example 9 Comparative 88.6 170.0 95.2 297.2 96.4 1.44 2.73 −24Example 10

Comparative Examples 9 and 10 are prepared by adding epoxidized soybeanoil as an epoxidized oil to the plasticizer compositions of Examples 2and 5, respectively. Referring to Table 4, it can be confirmed, thatComparative Examples 9 and 10 had poor low-temperature resistance,compared with the conventional product DIDP, and were decreased inplasticization efficiency, significantly decreased in retention oftensile strength and significantly decreased in elongation rate,compared with the examples in which epoxidized oil was not added.

Accordingly, it was confirmed that, in the case of the plasticizercomposition in which the trimellitate-based plasticizer is mixed withthe citrate-based plasticizer, the number of carbon atoms of eachmaterial is necessarily controlled, and a citrate-based plasticizer towhich an acetyl group is not bonded should be used as the citrate-basedplasticizer, and the addition of the epoxidized oil is not preferable interms of the quality of the plasticizer.

While the present invention has been described in detail with referenceto exemplary embodiments of the present invention, it should beunderstood by those of ordinary skill in the art that the scope of thepresent invention is not limited thereto and various forms ofmodification and alternation based on the fundamental ideas of thepresent invention defined by the accompanying claims are also includedwithin the scope of the present invention.

1. A plasticizer composition, comprising: a trimellitate-basedplasticizer represented by Formula 1; and a citrate-based plasticizerrepresented by Formula 2, wherein the plasticizer composition does notcontain epoxidized oil:

wherein, in Formula 1, R₁ to R₃ are each independently an alkyl grouphaving 4 to 10 carbon atoms,

wherein, in Formula 2, R₄ to R₆ are each independently an alkyl grouphaving 5 to 9 carbon atoms, and R₇ is hydrogen.
 2. The plasticizercomposition of claim 1, wherein the trimellitate-based plasticizer andthe citrate-based plasticizer are included at a weight ratio of 90:10 to10:90.
 3. The plasticizer composition of claim 1, wherein thetrimellitate-based plasticizer and the citrate-based plasticizer areincluded at a weight ratio of 70:30 to 30:70.
 4. The plasticizercomposition of claim 1, wherein R₁ to R₃ in Formula 1 are eachindependently selected from the group consisting of a normal butylgroup, an isobutyl group, a normal pentyl group, an isopentyl group, anormal hexyl group, a normal heptyl group, an isoheptyl group, a normaloctyl group, an isooctyl group, a 2-ethylhexyl group, a normal nonylgroup, an isononyl group, a 2-propylheptyl group, and an isodecyl group.5. The plasticizer composition of claim 1, wherein R₄ to R₆ in Formula 2are each independently selected from the group consisting of a pentylgroup, an isopentyl group, a hexyl group, an isohexyl group, a heptylgroup, an isoheptyl group, a normal octyl group, a 2-ethylhexyl group, anormal nonyl group and isononyl group.
 6. A resin composition,comprising: 100 parts by weight of a resin; and 5 to 150 parts by weightof the plasticizer composition of claim
 1. 7. The resin composition ofclaim 6, wherein the resin is one or more selected form the groupconsisting of ethylene vinyl acetate, polyethylene, polypropylene,polyketone, polyvinyl chloride, polystyrene, polyurethane, and athermoplastic elastomer.
 8. The resin composition of claim 6, whereinthe resin composition includes an epoxidized oil in an amount of lessthan 5 parts by weight with respect to 100 parts by weight of theplasticizer composition.